摘要
As cold-formed steel has the highest strength-to-weight ratio of any material,ultra-high strength martensitic steel is attracting great interest from global car manufacturers. This paper explores the effects of the quenching and over-aging temperatures on the strength and cold bendability of C-Mn-Si martensitic steel. Due to its high carbon content,water-quenched C-Mn-Si martensitic steel has high hardenability and can obtain ultra-high tensile strength and uniform martensitic morphology when the water-quenching temperature is higher than 710 ℃.Increasing the over-aging temperature of this experimental steel decreases its tensile strength,increases the total elongation,and first increases then decreases the yield point until reaching a peak at 180 ℃. Besides,when increasing the over-aging temperature,the bendability of this experimental steel initially improves and then decreases,and reaches its optimal bendability at an over-aging temperature of 180 ℃. Based on SEM characterization and a microhardness distribution analysis,the over-aging temperatures were found to affect the size of the carbides and differences in the microhardness of the experimental steel. Therefore,they have significant influence on bendability.
As cold-formed steel has the highest strength-to-weight ratio of any material,ultra-high strength martensitic steel is attracting great interest from global car manufacturers. This paper explores the effects of the quenching and over-aging temperatures on the strength and cold bendability of C-Mn-Si martensitic steel. Due to its high carbon content,water-quenched C-Mn-Si martensitic steel has high hardenability and can obtain ultra-high tensile strength and uniform martensitic morphology when the water-quenching temperature is higher than 710 ℃.Increasing the over-aging temperature of this experimental steel decreases its tensile strength,increases the total elongation,and first increases then decreases the yield point until reaching a peak at 180 ℃. Besides,when increasing the over-aging temperature,the bendability of this experimental steel initially improves and then decreases,and reaches its optimal bendability at an over-aging temperature of 180 ℃. Based on SEM characterization and a microhardness distribution analysis,the over-aging temperatures were found to affect the size of the carbides and differences in the microhardness of the experimental steel. Therefore,they have significant influence on bendability.
